1. Technical Field
This invention relates generally to a manifold system for mounting pressure sensing transmitters, and more particularly such a manifold system having separate common base and interchangeable functional manifold components.
2. Background Art
Multi-valve manifolds are typically used to mount pressure-sensing devices, such as Rosemount.RTM. Coplanar.TM. style pressure transmitters. For example, U.S. Pat. No. 5,277,224 issued Jan. 11, 1994 to Peter B. Hutton, et al. discloses a five-valve manifold for use with a pressure sensing apparatus. Other arrangements include the IntelliMount.TM. System, manufactured by Anderson Greenwood, and the Model 305 and 306 family of manifolds manufactured by Rosemount, Inc. The Model 305 and 306 manifolds require assembly with a transmitter prior to arrival of the assembly on-site, thus prohibiting connection of process lines to the manifold prior to installation of the transmitter. Furthermore, none of the above-referenced manifolds permit a functional manifold change without involving the manifold-to-process line connections. A further disadvantage of the IntelliMount.TM. manifold arrangement is that condensate cannot be fully drained from all pressure cavities to avoid potential calibration errors in the pressure sensing transmitter.
It is therefore desirable to have a two-piece manifold system which allows pressurizing of process lines with a base manifold component of the system in place, prior to a transmitter arriving on site. It is further desirable to have a functional control manifold component that attaches directly to the transmitter, and can be assembled with the transmitter at the factory or shop whereat it can be accurately torqued to the value required by the transmitter manufacturer. Pre-attachment of the functional manifold also protects the transmitter sensing foils during subsequent shipment and installation of the transmitter onto a pre-installed base manifold. Additionally, provision of a separate functional manifold, allows functional manifold changes without compromising the base manifold and possible shut down of a process system as a result of open pressure lines. It is further desirable to have a two-piece manifold system for mounting pressure-sensing transmitters in which condensate will fully drain from all pressure cavities to avoid potential errors during calibration of the pressure transmitting apparatus.